This is one of the most widely reported iPhone 7 problems. There are multiple threads on the Apple discussion forums full of iPhone 7 owners who have reported this particular problem. People have said that incoming audio sounds distant, or it’s too low to hear. Enough people have even made complaints about this that Apple has since updated a support page in an attempt to help people with sound issues.
1, Go to Settings > Sounds and drag the Ringer And Alerts slider to turn the volume up.
2, If you can get audio out of the speaker, there are several other things you can try:
1), Check the Ring/Silent switch on the side of the phone to make sure it’s not set to Silent (Orange).
2), Make sure your case isn’t blocking the speaker.
3), Restart your iPhone.
4), Clean any dirt, dust, or debris out of the speaker.
5), Launch an app that plays audio or sound effects and adjust the volume using the volume keys or Control Center controls.
3, If you can’t get sound out of the speaker, or nothing changes after trying the aforementioned methods, reach out to Apple Support.